This invention relates to a network for providing inter-regional or nationwide paging by interconnecting terminals, each of which provides local paging service.
The use of paging to contact a person who is away from his home or business is gaining increased acceptance. The availability of paging began locally. Paging service can be provided by a locality if it has a paging terminal. The terminal can be contacted through the telephone system by a person wishing to reach a subscriber carrying a pager. To reach a subscriber, a person would dial a number which accesses the terminal. The telephone number identifies the subscriber to be contacted with a page. Depending upon the system, provisions may be made for sending coded messages, voice messages or merely beeping the subscriber. After the terminal has received a page, it transmits a sequence of tones or binary digits over a radio channel. Each pager has a unique sequence which it recognizes. Upon recognizing the unique sequence of tones or binary digits, the pager will be beeped. It may also have a voice message, a numeric display or an alpha display in addition to the beep.
The memory of the terminal must store the information which identifies the pager corresponding to each individual phone number. The memory must also store information specific to each pager. This includes data identifying the type of pager, the tone combination (sequence) for addressing the pager and, for billing purposes, the address of the subscriber and a record of the time used in making pages.
There has been in interest in expanding the availability of paging to beyond the local area served by a single terminal. Several methods have been proposed for providing such a paging system. One method for expanding the coverage from a single terminal to a second terminal would be for the two terminals to share time on each of their transmitter systems. A control line would be run from each terminal to the transmitter in the other locality. An external clock would be necessary for allocating the time so that each terminal could share the transmitter time on each of the transmitters. This system has the obvious disadvantage of delaying or interrupting the local paging service while the other station is using the transmitter to send out its pages. Furthermore, expansion beyond a couple cities would require an extensive system of expensive cables.
Another method which could be used to expand paging coverage beyond a single locality would be to provide each customer with more than one telephone number which could be dialed to reach the subscriber. Each phone number would call up a different terminal in a different locality. At each terminal only one number would need to be added to the data base for each inter-regional subscriber to handle the inter-regional paging. This method would however provide many disadvantages to the persons using the system. A person would have the inconvenience of having to remember more than one telephone number. Furthermore, the out of the area numbers would generally be an expensive long distance phone call.
The most commonly used system for connecting paging terminals from several localities is to add a special encoder, trunk circuits and data base memory to the terminal at each of the localities. Pages received from an outside locality may be mixed into the gueue of the receiving locality's transmitter system. Thus, the inter-regional pages do not interrupt the normal flow of the system. In this method, the customer conveniently needs only to dial one number to effect an inter-regional page. If each terminal in the network of terminals has sufficient voice recording mechanisms available, tone and voice as well as tone only pages may be sent across the link between the localities. When more than two localities are linked together, a difficulty arises in this system. As shown in FIG. 1, when three cities are connected, each of the three terminals at the different cities must contain two encoders and two trunk lines to the other cities as well as additional memories for each terminal in the system. The trunk lines are expensive phone line circuits. They allow uninterrupted traffic flow between the localities. As the number of localities increases, the cost and manageability of such a networking scheme would be rather unruly.
Another proposal for providing inter-regional or nationwide paging is disclosed in U.S. Pat. No. 4,178,476 (Frost). In the Frost system, a master transit station can communicate pages to and from several base stations. This hub and spoke arrangement has several problems. In setting up a system among various localities, political problems may arise in the determination of which locality is going to be the master terminal. The communications company located at the master terminal would financially benefit from the increased use of its terminal to receive and send out inter-regional pages. Furthermore, each of the base systems would have the burden of paying for a communication line to hook up with the master terminal. The task of choosing a master terminal might thus lead to political squabbles between the various localities and common carrier companies.
Another disadvantage with the Frost system would arise if the master terminal should become inoperative for some reason. If this should happen the entire inter-regional paging system would be brought to a standstill. The integrity of the master terminal would be essential.
Plans are being made by the Federal Communications Commission to set aside the 900 MHz band for exclusive use by nation-wide paging. When this system is implemented, each subscriber will have the burden of obtaining a new pager which receives signals in the 900 MHz band. In addition, new paging terminals will be needed throughout the nation. Although this may eventually become an accepted nation-wide paging system, it may take several years before it can be implemented.